This project provides support for the participation of the Radiotherapy Division of the University of Puerto Rico in the Radiation Therapy Oncology Group. This organization is constituted by a national group of academic institutions involved in prospective clinical research in radiation therapy of cancer. The University of Puerto Rico began its participation in the Radiation Therapy Oncology Group early in 1972. Study cases are contributed by the University Hospital, the San Juan V.A. Hospital, the San Juan City Hospital, and the Radiotherapy Institute of the Metropolitan Hospital, all of which form part of the academic radiation therapy program.